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Work Done by a Varying Force. So far. Forces are constant. Work done = F·s. Consider. Force on the spring varies as the length increases As the spring is displaced the force varies. Let’s look at the graph. Area under the graph = F ·s Area under the graph = Work done.
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So far... Forces are constant Work done = F·s
Consider... • Force on the spring varies as the length increases • As the spring is displaced the force varies
Let’s look at the graph • Area under the graph = F·s • Area under the graph = Work done
Let’s look at the graph • Area under the graph = Work done • Work done to stretch a spring = ½ Fx
Spring Extension • Force is proportional to extension • Slope of the graph is constant • Slope = Spring constant • a.k.a. force constant • Equation
Strain Energy • Stored energy due to stretching or compression • Work-Energy Theorem • Work done on the spring • Work done by the spring